This is a companion thread to;
where I described a similar situation with a '66 L-36. I finally convinced Hector that we had to pull the distributor and disassemble to find the issue because it was only providing 20 degrees centrifugal instead of the OE 30... bottom line is this dist. appeared to be assembled from a box of junk parts.
The cam assembly was 522, and I think many of us believe that the last two digits indicate the total centrifugal advance available and the most common are 524 and 530 - at least on C2s.
So we drove over to David Sokolowskils place. Hector has a very good relationship with David and when we arrived David was laying out what was a milk bottle crate full of these parts on a table. My initial objective was to get a 530 or a 532, but as I looked at the rows I found numbers that I had never seen before, like a 518, 536, and 740 (or was it 540). I had no idea so many existed. My '77 vintage P & A catalog shows nine, but there must have been more different ones in this collection. I suggested to David that some had come for other GM divisions (all use the same family of parts for V8 distributors), but he said that they ALL came from Corvette tach drive distributors. You could clearly see that there was a correlation with the length of the slot with the last two digit of the number.
My objective changed to get close to the '67 (not '66) spark advance map, so I wanted a part that ended with 32, but there were two types, 532 and 732, and so far we have not been able to find any differences, but we're not done measuring or scratching our heads. I picked out a dozen parts for more thorough evaluation. I was getting late and David said to take them all home, do our analysis and return what we didn't want. Great! We said we'd see him next week when we get back at the job.
So my question is does anyone know why there are two "32 degree" cam assemblies, and why there are some others with the same last two digits, but either a 5 and a 7 as the first?
Before we drove out to David's place I called Lars to consult with him. Hector's '66 CSM did not show where the #1 plug wire was indexed on the cap. It was the same as a SB when we pulled it out and I wanted to verify. Lars said yes.
Hector has two other '66 L-36 distributors, both mag pulse for a TI One is used and one is "rebuilt" by some Corvette outfit. Both these and the Frankenstein we pulled off his engine had the gear dimple opposite the rotor tip. Lars said it should be pointing toward the rotor tip, just like a SB, but if it isn't you don't run into the initial advance limit issues like on a SB. Nevertheless, we'll assemble as it properly with the dimple pointing the same direction at the rotor tip.
Some of you may not know that TI and single point distributors use the same base, so we are going to use the best parts from all three along with what we get from David to assemble a good distributor with as close to the '67 L-36 spark advance map that had 2 degrees more centrifugal and 4 degrees less vacuum advance than '66. Lars is sending one of his vacuum advance limiter kits if we decide to need to reduce the max '66 vacuum advance of 16 @ 12" to 12 at 12" per the '67 map.
Then we'll see if we can quicken the curve without detonation.
Duke
where I described a similar situation with a '66 L-36. I finally convinced Hector that we had to pull the distributor and disassemble to find the issue because it was only providing 20 degrees centrifugal instead of the OE 30... bottom line is this dist. appeared to be assembled from a box of junk parts.
The cam assembly was 522, and I think many of us believe that the last two digits indicate the total centrifugal advance available and the most common are 524 and 530 - at least on C2s.
So we drove over to David Sokolowskils place. Hector has a very good relationship with David and when we arrived David was laying out what was a milk bottle crate full of these parts on a table. My initial objective was to get a 530 or a 532, but as I looked at the rows I found numbers that I had never seen before, like a 518, 536, and 740 (or was it 540). I had no idea so many existed. My '77 vintage P & A catalog shows nine, but there must have been more different ones in this collection. I suggested to David that some had come for other GM divisions (all use the same family of parts for V8 distributors), but he said that they ALL came from Corvette tach drive distributors. You could clearly see that there was a correlation with the length of the slot with the last two digit of the number.
My objective changed to get close to the '67 (not '66) spark advance map, so I wanted a part that ended with 32, but there were two types, 532 and 732, and so far we have not been able to find any differences, but we're not done measuring or scratching our heads. I picked out a dozen parts for more thorough evaluation. I was getting late and David said to take them all home, do our analysis and return what we didn't want. Great! We said we'd see him next week when we get back at the job.
So my question is does anyone know why there are two "32 degree" cam assemblies, and why there are some others with the same last two digits, but either a 5 and a 7 as the first?
Before we drove out to David's place I called Lars to consult with him. Hector's '66 CSM did not show where the #1 plug wire was indexed on the cap. It was the same as a SB when we pulled it out and I wanted to verify. Lars said yes.
Hector has two other '66 L-36 distributors, both mag pulse for a TI One is used and one is "rebuilt" by some Corvette outfit. Both these and the Frankenstein we pulled off his engine had the gear dimple opposite the rotor tip. Lars said it should be pointing toward the rotor tip, just like a SB, but if it isn't you don't run into the initial advance limit issues like on a SB. Nevertheless, we'll assemble as it properly with the dimple pointing the same direction at the rotor tip.
Some of you may not know that TI and single point distributors use the same base, so we are going to use the best parts from all three along with what we get from David to assemble a good distributor with as close to the '67 L-36 spark advance map that had 2 degrees more centrifugal and 4 degrees less vacuum advance than '66. Lars is sending one of his vacuum advance limiter kits if we decide to need to reduce the max '66 vacuum advance of 16 @ 12" to 12 at 12" per the '67 map.
Then we'll see if we can quicken the curve without detonation.
Duke
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